So far we have seen properties which describe a part visual, as well as those you can make yourself. But, as mentinoed on the last card, properties describe everything about a part and since our parts our "live" that means that even dynamic behavior is encapsulated in properties. This means that the way you tell a button to turn blue and the way you tell it to start dancing around is really much the same (as long as you've described what you mean by "dancing around" of course).

We'll only at examples here - "wants-move," "target" and "stepping" - but hopefully this will give you a flavor of the richness of how these properties come together to descrive the Simpletalk world.

wants-move

You've probably noticed how you can move many parts around when you open up the halo (at least parts which are not fixed in some sort of layout scheme like list-row or list-column). But when the halo is open, the part is in editing mode, and you might want to be able to move it around in general. For example, imagine you want to make a controller to steer a plane or move a paddle around for pong. It would be inconvenient if you had to open the halo every time you want to do that. For this you can simply set "wants-move" to true and the part will respond to mouse movements. (We are likely going to implement a "want-*" for many common peripherals - drag, click, keyboard etc - in the future and allow you to make your own.)

target

The "target" property is just like what it sounds like. It defines a relationship between any part and another which can then be referred to in a script. For example, imagine you make a really cool menu for text editing with buttons, inputs etc and you use this menu to edit a field, type up and style your story. But what if you want to change the context of the menu, what if someone wants to copy it and use it in their own world? Well for that you just change the "target" property by specifying a new part. For example if you open the scripting editor in the "I am alive!" button on the right you will see commands like

tell target to set "background-color" to "blue"

and if the target the specified the above command change its background color. There are two ways to specify a target. First, just like other properties, you can use the "set" command with an object specifier, such as in the example on the right (you can learn more about object specifiers in the "Language" stack). And another is by clicking on the halo target icon and subsequently selecting the highlighted part. Note, "target" does not appear in the properties pane of the editor since object specifiers tend to be long strings which can clutter the view (but we might change this in the future!).

stepping

When the "stepping" property is set to true, the corresponding part will start receiving a "step" message every 500milliseconds. You can change the frequency by setting the "stepTime" property to whatever millisecond value you'd like. And then you can script against "step" with an "on step" message handler, which will run over and over until "stepping" is set back to false. Try telling the button on the right to set "stepping" to true and see what happens. Then open up the script and see how it works. (Note: ctrl-c will set "stepping" to false in all parts in your world; this is a handy way to stop runaway processes...).

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